In a wireless multiple access communication system, wireless terminals contend for system resources in order to communicate with a common receiver over an uplink channel. An example of this situation is the uplink channel in a cellular wireless system, in which wireless terminals transmit to a base station receiver. When a wireless terminal transmits on the uplink channel, it typically causes interference to the entire system, e.g., neighboring base station receivers. Since wireless terminals are distributed, controlling the interference generated by their transmission is a challenging problem.
Many cellular wireless systems adopt simple strategies to control uplink interference. For example CDMA voice systems (e.g., IS-95) power control wireless terminals in such a manner that their signals are received at the base station receiver at approximately the same power. State-of-the-art CDMA systems such as 1xRTT and 1xEV-DO allow for wireless terminals to transmit at different rates, and be received at the base station at different powers. However, interference is controlled in a distributed manner which lowers the overall level of interference without precisely controlling those wireless terminals that are the worst sources of interference in the system.
This existing body of interference-control approaches limits the uplink capacity of wireless systems.
It would be useful if a base station could be provided with information that could be used in determining the amount of signal interference that will be created in neighboring cells and/or sectors when a transmission occurs and/or determining the amount of interference a wireless terminal is likely to encounter due to signal interference. It would be particularly desirable if information which can be used for interference determination purposes could be supplied by one or more wireless terminals to a base station.
Loading affects interference considerations in a wireless communications system. It would be beneficial if wireless terminals and/or base stations communicated such information. It would also be beneficial if wireless terminals and/or base stations utilized such loading information in determining interference levels.
Various received different types of downlink broadcast reference signals may be usable at different times to a wireless terminal which is to communicate interference information to a base station. It would be beneficial if methods and apparatus supported utilizing different types of broadcast reference signals in determining interference information and/or tailoring the reporting calculations to accommodate a current set of conditions.